Add fix for GPS rollover bug, closes #78

bfabiszewski · Aug 23, 2020 · b4ce161 · b4ce161
1 parent c39c3a9
commit b4ce161
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diff --git a/app/src/main/java/net/fabiszewski/ulogger/LocationHelper.java b/app/src/main/java/net/fabiszewski/ulogger/LocationHelper.java
@@ -32,6 +32,13 @@ class LocationHelper {
     private final Context context;
     private final LocationManager locationManager;
 
+    // millis 1999-08-21T23:59:42+00:00
+    private static final long FIRST_ROLLOVER_TIMESTAMP = 935279982000L;
+    // millis 2019-04-06T23:59:42+00:00
+    private static final long SECOND_ROLLOVER_TIMESTAMP = 1554595182000L;
+    // 1024 weeks in milliseconds
+    private static final long ROLLOVER_MILLIS = 1024 * 7 * 24 * 60 * 60 * 1000L;
+
     private boolean liveSync = false;
     private int maxAccuracy;
     private float minDistance;
@@ -249,6 +256,20 @@ boolean isLiveSync() {
         return liveSync;
     }
 
+
+    /**
+     * Fix GPS week count rollover bug if needed
+     * https://galileognss.eu/gps-week-number-rollover-april-6-2019/
+     * @param location Location
+     */
+    static void handleRolloverBug(Location location) {
+        long gpsTime = location.getTime();
+        if (gpsTime > FIRST_ROLLOVER_TIMESTAMP && gpsTime < SECOND_ROLLOVER_TIMESTAMP) {
+            if (Logger.DEBUG) { Log.d(TAG, "[Fixing GPS rollover bug: " + gpsTime + "]"); }
+            location.setTime(gpsTime + ROLLOVER_MILLIS);
+        }
+    }
+
     /**
      * Logger exceptions
      */

diff --git a/app/src/main/java/net/fabiszewski/ulogger/LoggerService.java b/app/src/main/java/net/fabiszewski/ulogger/LoggerService.java
@@ -300,6 +300,8 @@ private class mLocationListener implements LocationListener {
         public void onLocationChanged(Location location) {
             if (Logger.DEBUG) { Log.d(TAG, "[location changed: " + location + "]"); }
 
+            LocationHelper.handleRolloverBug(location);
+
             if (meetsCriteria(location)) {
                 lastLocation = location;
                 DbAccess.writeLocation(LoggerService.this, location);